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Chapter Summary

Rectilinear Figures

ICSE · Class 9 · Mathematics

Summary of Rectilinear Figures for ICSE Class 9 Mathematics. Key concepts, important points, and chapter overview.

39 questions30 flashcards5 concepts

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A diagram illustrating the difference between convex and concave polygons, highlighting the interior angles.
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Overview

Rectilinear means along a straight line, in a straight line, or forming a straight line. A rectilinear figure is a plane figure bounded by straight lines. A polygon is a closed plane figure bounded by at least three line segments. The chapter builds the idea of polygons first, then studies their ang

Key Concepts

A polygon is a closed plane

A polygon is a closed plane figure bounded by at least three line segments. It is named by the number of sides, such as triangle, quadrilateral, penta

If each angle of a polygon

If each angle of a polygon is less than 180°, it is a convex polygon. If at least one angle is greater than 180°, it is a concave polygon. Unless othe

In a polygon of n sides

In a polygon of n sides, the sum of the interior angles is equal to (2n - 4) right angles. This rule works for regular and non-regular polygons, and i

If the sides of a polygon

If the sides of a polygon are produced in order, the sum of the exterior angles is 4 right angles, which is 360°.

If all the sides and all

If all the sides and all the angles of a polygon are equal, it is called a regular polygon. Each interior angle is (2n-4) rt. angles / n and each exte

Learning Objectives

  • Identify rectilinear figures and polygons.
  • Classify polygons by number of sides.
  • Distinguish convex and concave polygons.
  • Use the interior-angle and exterior-angle sum rules for polygons.
  • Find unknown angles and number of sides in polygon problems.

Frequently Asked Questions

What are the important topics in Rectilinear Figures for ICSE Class 9 Mathematics?
Rectilinear Figures covers several key topics that are frequently asked in ICSE Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.
How to score full marks in Rectilinear Figures — ICSE Class 9 Mathematics?
Understand the core concepts first, then work through the 39 practice questions available for this chapter. Revise formulas and definitions regularly, and use flashcards for quick recall before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.

More resources for Rectilinear Figures

All 28 chapters — ICSE Class 9 Mathematics Chapter Summary

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